Over the past ten years, the amount of heat generated by individual components within computer systems has increased dramatically. For example, in 1995 when Intel Corporation introduced the ATX form factor specification, central processing units (CPUs) dissipated around 10 watts of heat. Some ten years later when Intel introduced the BTX form factor specification, CPUs dissipated nearly 150 watts of heat. Along the same lines, the average high-performance graphics card now dissipates around 80 watts of heat, whereas graphics cards from 1995 dissipated about one-tenth that amount. As such, it is becoming increasingly more important to adequately cool high-power components within the computer chassis to ensure reliability and increase the performance of each component.
FIG. 1 shows a computer “tower” chassis in accordance with the ATX form factor specification. Accordingly, chassis 100 has input/output (I/O) slot area 110 providing slots in which peripheral interface cards can be inserted. When slots are unoccupied, solid plates cover the holes as shown by blocked-off I/O slot 115. 5.25 inch optical drives are inserted in optical drive area 120, and 3.5 inch hard disk drives (HDDs) are inserted in HDD area 125. Chassis 100 also includes power supply unit (PSU) 130, which supplies power to motherboard 135. PSU fan 165 helps to cool PSU 130 by directing air through the power supply enclosure and out vent 160, shown in FIG. 1 as PSU airflow 185. System memory 140 and CPU 145 are detachably coupled to motherboard 135, which has connectors aligned with the slots comprising I/O slot area 110 for receiving peripheral interface devices. On such peripheral interface device is graphics card 150.
As shown in FIG. 1, vent 155 and vent 160 are placed on the front and rear of the chassis to permit air to flow through chassis 100. Chassis fan 170 creates main airflow 175, which enters through vent 175 and exhausts through vent 160. However, not all the air entering vent 155 is exhausted out vent 160, creating recirculation airflow 180 and 182. As such, hot air from CPU 145 is directed back over some of the larger heat-generating components: system memory 140 and graphics card 150. Not only does the recirculation of hot air within the chassis reduce the reliability and performance of most components, but it also significantly reduces the potential heat dissipation from each component by increasing the ambient air temperature within the chassis. Moreover, trapped air pockets 190, 192, and 194 around the graphics card, HDD, and optical drives further increase the temperatures around these components. As such, a chassis in accordance with the ATX specification creates a significant reliability and performance bottleneck for system builders.
FIG. 2 shows a computer “tower” chassis in accordance with the BTX form factor specification. Similar to the ATX chassis 100 of FIG. 1, chassis 200 of FIG. 2 includes I/O slot area 210 with blocked-off I/O slot 215, optical drive area 220, HDD area 225, and PSU 230 with PSU fan 265 for creating PSU airflow 285 that exhausts through vent 260. Also, system memory 240, CPU 245, and graphics card 250 are detachably coupled to motherboard 235. Main airflow 275 is created by chassis fan 270, which draws air into chassis 200 through vent 255 and exhausts the air through vent 257.
However, unlike chassis 100 conforming to the ATX specification, chassis 200 includes thermal module 272 for directing main airflow 275 over CPU 245. Nonetheless, not all the air entering the chassis through vent 255 exits through vent 257. As such, recirculation airflow 280 and 282 directs hot air back over system memory 240 and graphics card 250. Moreover, chassis 200 creates trapped air pockets 290, 292, and 294, which increases the ambient air temperature around the main heat-generating components. Thus, although the BTX specification provides more effective cooling of the CPU over the ATX specification, the reliability and performance of the main heat-generating components are still effected to much the same degree as with the ATX specification.
FIG. 3 shows a more detailed view of airflow within the I/O area of a computer chassis conforming to either the ATX or BTX specification. A number of peripheral interface devices are connected to chassis 300 as shown in FIG. 3, creating a number of blocked-off I/O slots 310. More specifically, the peripheral interface devices include graphics card 320, peripheral interface device 330, and peripheral interface device 340. Graphics card fan/duct assembly 350 connected to graphics card 320 directs heated air 360 from the top side of the graphics card out vented I/O slot 370. Although this helps dissipate some heat from the graphics card, trapped air pockets 390 and 392 are formed between the peripheral interface devices which significantly hinders overall heat dissipation from graphics cards and other peripheral interface devices. Moreover, this effect is amplified given that chassis airflow 380 flowing to the I/O area is pre-heated given the high ambient air temperatures with a chassis conforming to either the ATX or BTX specification as discussed above.